A multifunctional filter for the simultaneous removal of fly-ash and NOx from incinerator flue gases

A multifunctional reactor for fly-ash filtration and simultaneous catalytic removal of NOx and VOCs from incinerator flue gases was conceived and investigated. It is based on a high-temperature resistant polymeric filter bag, enclosing a catalytically activated ceramic foam structure. Catalyst development has been pursued so as to reach high NOx and VOC removal efficiencies (> 80%) at the filter bag operating temperatures (200-210 degreesC) and for superficial velocities of industrial interest (10-60 Nm(3) m(-2) h(-1)). Combinations of MnOx (.) CeO2 and V2O5 (.) WO3 (.) TiO2 catalysts species were found to be successful to these merits. Catalyst deposition inside selected foam substrates was operated by impregnation with a catalyst suspension, followed by microwave drying and calcination. Tests on the catalytic performance of the prepared catalytic foams on real flue gases showed promising, though improvable results. NO and benzene conversions close to 80% were obtained with a MnOx (.) CeO2-V2O5 (.) WO3 (.) TiO2 catalysed foam operating at 30 Nm(3) m(-)2 h(-1). Some detrimental effects of SO2 on the catalyst activity suggest its preliminary removal by e.g. dry scrubbing. Furthermore, evidence of some pore plugging by the catalyst was found by direct SEM observation as well as by simple simulation studies. This points the way towards further amelioration of the reactor performance by an improved catalyst distribution within the foam. (C) 2004 Elsevier Ltd. All rights reserved.